Multiwall bag construction



Sept. 13, 1960 R. F. SEARLE MULTIWALL BAG CONSTRUCTION Filed July 5,1955 INVE NTOR figzfierz Jearle 2 4e,

M 0! MW ATTORNEYS I l I United States Patent MULTIWALL BAG CONSTRUCTIONRobert F. Searle, C'anajoharie, N.Y., assignor to Arkell and Smiths, acorporation of New York Filed July 5, 1955, Ser. No. 519,874

3 Claims. (Cl. 229-66) This invention relates to the manufacture ofmultiwall bags wherein the paper adjacent the mouth of the bag is soweakened that the top of the bag may be readily torn ofi? by hand in onesmooth, even movement.

The type of multiwall bag to which this invention relates is a so-calledgusseted bag which is ordinarily sealed shut by means of a line ofstitching running across the top of the bag. In theory, such a bag isopened by unraveling the stitching, but this is difficu-lt to do and asfrequently happens it is necessary to get a knife or a pair of scissorsand cut the top of the bag off below the line of stitching.

With bags made in accordance With my invention, the top may be readilytorn oil by hand in one smooth, even movement. This effect is achievedby so weakening the paper at one side of the bag adjacent its mouth thatthe paper can be readily torn by hand but the paper is weakened in sucha way that there is no danger of leakage, even if the bag is filled withfine powder. Weakening the bag so that it will readily tear is achievedby means of a small slit positioned at the side of the bag and by meansof a plurality of small holes which assist in leading the tearing fromthe slit up to the line of sewing across the top of the bag.

As is known, the strongest part of a multi-wall bag and the mostdifiicult part to tear is located in the area of the gusset at the sideof the bag where the paper is doubled over on itself. I have found thatthe only satisfactory way of tearing through the crease line of thegusset so that tearing will start at a designated spot is to cut a slitall the way through the layers of paper in the gusset crease lines. Inthis way I achieve accurate control of tearing so that it starts at apredetermined point and once tearing is started the momentum of thetearing movement is such that tearing may be readily sustained andcontrolled by means of the line of small holes, which lead the tearingup towards the line of stitching across the top of the bag. As a result,in the structure of my invention, tearing is rigidly controlled along apredetermined line and the bag when torn open presents uniformly andevenly torn edges which are of great advantage for emptying the contentsof the bag. If tearing is not rigidly controlled there is a tendency forit to go off on a tangent and spiral down the side wall of the bag,which may result in loss of product.

A surprising thing about the structure of my invention is that althoughI actually slit the paper of the bag and punch small holes in it, noneof the contents leak from the bag during shipment and storage. I believethat this is a result of two factors. First of all I locate the weakenedportion of the bag in the area of the gusset adjacent the mouth of thebag where the paper is strongest and as a result there is no tendency toincrease the chance of the bag splitting open when it is handled. Thesecond factor is that there are two or more plies of paper in the sidewall of the bag and I believe that the displaced fibers in successivelayers of paper tend to close the slit ICC and holes sufiiciently sothat no leakage occurs. In any event, bags made in accordance with myinvention filled with lbs. of cement were subjected to rigorous testsand none of the bags failed and there was :no leakage of contents fromthe bags.

My invention may be readily understood by reference to the accompanyingdrawings in which Fig. l is an isometric view of the top portion of amultiwall bag tube illustrating the structure of my invention;

Fig. 2 is a front elevational view of the bag tube shown in Fig. 1 whichis closed on top by means of a separate strip of paper which is foldedover the mouth of the bag and sewed in place to close the open bagmouth; and

Fig. 3 illustrates the way in which the top of the bag of Fig. 2 may betorn oil by hand in accordance with my invention.

Referring now to the drawings, 10 is a top portion of a multiwall bagtube having two or more plies of paper or other bag forming material inthe side wall of the tube. Along each side of the tube is a gusset 12which is formed by folding a portion of the side wall inwardly into thebag tube and the infolded paper is then sharply creased to hold it inposition. In use, the bag tube is filled through the open mouth and thenclosed by means of a line of stitching 14 across the top of the bag. Astrip of paper 16 is ordinarily folded over the mouth of the bag andpasted down over the line of stitching on both sides of the bag. Ifdesired, the strip of paper may be applied before the bag is sewed andthe paper 16 is then caught in the line of stitching. If this is done nopasting is necessary.

In accordance with the present invention a small slit 18 is cut throughthe paper of the two outside crease lines 19 of gusset 12. Slit 18 mustbe deep enough to completely cut through all of the plies of paper inboth crease lines 19 and in general a slit that extends inwardly intothe side wall of the bag about A; to A of an inch and preferably about 7inch is suflicient. Slit 18 may be made deeper than this, but a deeperslit serves no useful purpose and it only tends to weaken the paper inthe side wall of the bag. Slit 18 terminates at a point removed from theline of stitching acros the top of the bag but in proximity thereto andat a point adjacent to a line of a plurality of holes 20 which leadinwardly and upwardly away from the slit towards the line of stitching14 across the top of the bag. The line of holes 20 tenninatesapproximately at the line of stitching 14. Holes 20 are about the sizeof the holes formed by the needle employed for sewing the bag shut andas in the case of slit 18, holes 2%) preferably penetrate through all ofthe plies of the paper in the gusset and both side walls of the bag.Space 22 between each hole 20 and. between slit 18 and the hole 20adjacent the slit may be the same size as the spaces between the holesin the line of stitching 14 across the top of the bag. With ordinarysewing machines now in use the holes in the line of stitching across thetop of the bag that close the bag tube are approximately to of an inchin diameter and the space between the periphery of adjacent holes isabout of an inch. Best results are achieved in carrying out my inventionby making holes 20 about the same size and about the same distance apartas those in the line of stitching 14 across the top of the bag. It willbe understood, however, that any dairable arrangement and spacing ofholes 20 may be used as long as the paper between the holes can be tornaway by hand and as long as there is no tendency for the bag to leakduring shipment and storage.

It can be readily appreciated that slit 18 and holes 20 weaken the paperin the side wall of the bag, but I have found that the paper in thegusset area adjacent line of stitching 14 is strong enough to withstandsuch weakening without increasing the chance of the bag splitting openduring the handling incident to shipment and storage. Referring to thedrawings, it will be seen that slit 18 is located below the line ofstitching 14 across the top of the bag and the slit should be locatedwithin the area covered by the folded strip of paper 16 with the resultthat the slit and series of holes are concealed by the paper strip. Slit18 may be located immediately adjacent the line of stitching 14, but itmust be located far enough down to provide a good finger grip at the topof the closed bag above the slit. If desired, slit 18 may be directedupwardly at an angle toward the line of stitching 14.

As previously described hereinabove, holes 20 form a connecting linebetween slit 18 and the line of stitching 14, and in order to have thepaper tear smoothly and evenly it is impotrant that the space betweenthe last hole 20 and a hole in the line of stitching is no greater thatthe spacing between any two adjacent holes 20. Best results are achievedwhen the last hole 20 is positioned just below the line of stitchingwith the top of hole 20 in line with the bottom of the holes in the lineof stitching 14. When this is done the tearing is evenly and smoothlyled into the line of stitching across the top of the bag.

If desired holes 20 may be positioned in a straight line across the bagparallel to the line of stitching 14 but best results are achieved whenthe holes are directly upwardly towards the line of stitching as shownin the drawings.

It will be understood that the bag tube is sewed shut after slit 18 andholes 20 are positioned in the tube, but the location of holes 20relative to the line of stitching presents no problem since for anygiven filling operation the line of stitching 14 across the bag is inapproximately the same location on successive bags, and any small changein location of the line of stitching between successive bags may becompensated for by locating the top of the last hole 20 in line with theplace where the bottom of the holes in the line of stitching willordinarily cross the top of the bag for a given sewing operation.

With bags made in accordance with my invention it is only necessary tograsp the top of the bag tightly between the thumb and forefinger and bygiving it a quick jerk upwardly the paper will start tearing at slit 18and with the momentum of the tearing movement thereby obtained, tearingwill progress smoothly and evenly along the line formed by holes 20 andstitching 14 across the top of the bag. In the usual bag constructionthe separate strip of paper 16 at the top of the bag projects out beyondthe side edge of the bag and the projecting portion of the strip ofpaper may be used as a handle for tearing off the top of the bag.

It will be understood that I intend to cover all changes andmodifications of the preferred embodiment of my invention herein chosenfor the purpose of illustration which do not constitute departures fromthe spirit and scope of'my invention.

What I claim is:

1. In a bag of the type having walls of'a'pluralit'y of plies of paperhaving a portion of the wall along each side folded inwardly and sharplycreased to form a gusset with two outside crease lines that extend alongeach side of the bag from top to bottom, a separate strip of paperfolded over the top of the bag which covers the open mouth thereof andwhich projects out beyond one of the side edges of the bag and a line ofstitchingp'ositioned across the top of the bag adjacent the open mouththereof which passes through the strip of paper to attach it to theexterior of both side walls of the bag so that the strip of paper isheld in place to close the open mouth of the bag, a slit positioned ineach of the two outside crease lines of the gusset below the line ofstitching at that side of the bag from which the separate strip of paperprojects which slits are located in spaced relationship to the line ofstitching but adjacent thereto within the area at the top of the bagcovered by said separate strip of paper, said slits penetrating deeplyenough into the side wall of the bag to cut through all of the plies ofpaper in the two outside crease lines of the gusset but only far enoughto form an opening in the inner ply small enough so that substantialle'aka'ge'of product will not occur, each of said slits terminatingbelow the line of stitching across the top of the bag and in proximitythereto, and a plurality of spaced holes punched through all of theplies of paper in the gusset and side wall of the bag to form a seriesof holes that extend in a'line from the slits up to the line ofstitching across "the top of the bag to control tearing of the paperplies so that once tearing is started at the slits the tearing willcontinue along the line of said holes and thereafter follow the line ofstitching across the top of the bag whereby the top of the bag may betorn off by hand by jerking npwardly on the projecting end of the stripof paper which covers the open mouth of the bag. 7

2. A structure as specified in claim 1 in which the slits are positionedat an angle relative to the line of the side edge of the bag slopinginwardly and upwardly towards the line of stitching across the top ofthe bag.

3. A structure as specified in claim 1 in which the slits extendinwardly into the wall of the bag from about A; to A of an inch.

References Cited in the file of this patent UNITED STATES PATENTS1,155,740 Lacroix Oct. 5, 1915 2,099,425 Goodman Nov. 16, 1937 2,189,431Moore Febu'6, 1940 FOREIGN PATENTS 481,327 Canada Feb. 26, 1952 709,750Great Britain June 2, 1954 865,561 France Mar. 3, 1941

